The last decade has seen knowledge of the immune system and its regulation expand tremendously. One area of particular interest has been that of research on the proteins and glycoproteins which regulate the immune system. Perhaps the best known of these molecules, which are generically referred to as "growth factors", "cytokines", "leukotrines", "lymphokines", etc., is interleukin-2 ("IL-2"). See, e.g., U.S. Pat. No. 4,778,879 to Mertelsmann et al.; U.S. Pat. No. 4,490,289, to Stern; U.S. Pat. No. 4,518,584, to Mark et al.; and U.S. Pat. No. 4,851,512 to Miyaji et al. Additional patents have issued which relate to interleukin 1--("IL-1"), such as U.S. Pat. No. 4,808,611, to Cosman. The disclosure of all of these patents are incorporated by reference herein.
In order for molecules such as IL-2 and IL-1 to exert their effect on cells, it is now pretty much accepted that these must interact with molecules, located on cell membranes, referred to as receptors. Patents which exemplify disclosures of interleukin receptors include Honjo et al., U.S. Pat. No. 4,816,565; and Urdal et al., U.S. Pat. No. 4,578,335, the disclosures of which are incorporated by reference. Recently, Fanslow, et al., Science 248: 739-41 (May 11, 1990) presented data showing that the effect of IL-1 in vivo could be regulated via the administration of a soluble form of its receptor. The last paragraph of the Fanslow paper, the disclosure of which is incorporated by reference, describes the types of therapeutic efficacy administration of soluble IL-1 receptor ("IL-1R") is expected to have.
The lymphokine IL-9, previously referred to as "P40", is a T-cell derived molecule which was originally identified as a factor which sustained permanent antigen independent growth of T4 cell lines. See, e.g., Uyttenhove, et al., Proc. Natl. Acad. Sci. 85: 6934 (1988), and Van Snick et al., J. Exp. Med. 169: 363 (1989), the disclosures of which are incorporated by reference, as is that of Simpson et al., Eur. J. Biochem. 183: 715 (1989).
The activity of IL-9 was at first observed to act on restricted T4 cell lines, failing to show activity on CTLs or freshly isolated T cells. See, e.g., Uyttenhove et al., supra, and Schmitt et al., Eur. J. Immunol. 19: 2167 (1989). This range of activity was expanded when experiments showed that IL-9 and the molecule referred to as T cell growth Factor III ("TCGF III") are identical. IL-9 enhances the proliferative effect of bone marrow derived mast cells to "IL-3", as is described by Hultner et al., Eur. J. Immunol. and in U.S. patent application Ser. No. 498,182 filed Mar. 23, 1990 the disclosures of both being incorporated by reference herein. It was also found that the human form of IL-9 stimulates proliferation of megakaryoblastic leukemia. See Yang et al., Blood 74: 1880 (1989). Recent work on IL9 has shown that it also supports erythroid colony formation (Donahue et al., Blood 75(12): 2271-2275 (Jun. 15, 1990)); promotes the proliferation of myeloid erythroid burst formation (Williams et al., Blood 76: 306-311 (Sep. 1, 1990)); and supports clonal maturation of BFU.E's of adult and fetal origin (Holbrook et al., Blood 77(10): 2129-2134 (May 15, 1991)). Expression of IL9 has also been implicated in Hodgkin's disease and large cell anaplastic lymphoma (Merz et al., Blood 78(8): 1311-1317 (Sep. 1, 1990)).
The art teaches the cloning of receptors for various members of the interleukin family. Moseley et al. Cell 59: 335-348 (1989), teach the isolation of cDNA coding for IL-4 receptors, and analysis of both genomic DNA and RNA for these molecules. To do this, Moseley et al. worked with cells exhibiting up to 1 million receptor molecules per cell, and an N-terminal amino acid sequence for IL-4 receptor. Holmes et al., Science 253: 1278-1280 (1991), and Murphy et al., Science 253: 1280-1282 (1991) discuss cDNA for the IL-8 receptor. Murphy et al. proceeded via hybridization studies, using an oligonucleotide probe based upon rabbit IL-8R amino acid sequences to isolate the human counterpart. Holmes et al. used human neutrophil CDNA libraries followed by transfection in COS cells.
Gillis, "T-cell Derived Lymphokines" in Paul, ed., Fundamental Immunology, Second Edition (New York, 1989), at pages 632 et seq. gives an overview of interleukin receptors. This reference describes cDNA for the IL1 receptor, the IL2 receptor and the IL-6 receptor.
These studies indicate that several factors are important in attempting to identify and isolate a nucleic acid sequence coding for an interleukin receptor. Ideally, one has both the amino acid sequence for the receptor and a cell type with a high degree of expression of the receptor molecule.
In the case of the interleukin 9 receptor, while Druez et al., J. Immunol. 145: 2494-2499 (1990) have identified and characterized the receptor, an amino acid sequence of the molecule is not yet available. In addition, very few cell types are known which express IL9-R (Druez, su gra), and those that do, express it at very low levels. Thus, it is surprising that it now possible to identify and to isolate nucleic acid sequences which code for the interleukin 9 receptor. This is the key feature of the invention described herein, as will be seen from the disclosure which follows.